Film sealing and wrapping machine with rotary cut and seal jaw

ABSTRACT

The film sealing and wrapping machine with a rotary cut and seal jaw is provided. The rotary cut and seal jaw has an internal sliding mechanism which provides for smooth and quiet operation. The rotational speed of the jaw may be varied to increase through put and to provide for a title bag around products. The rotary cut and seal jaw may comprise a seal bar and pressure pad may both be spring loaded to self align the seal bar and pressure pad during the sealing and cutting process. Lastly, a gap defined by a belt disposed upstream and downstream of the seal bar and pressure pad may be mechanically linked to the pressure pad through a control carriage.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation patent application of U.S.patent application Ser. No. 12/427,654, filed on Apr. 21, 2009 now U.S.Pat. No. 8,087,220, the entire contents of which are incorporated hereinby reference.

STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

Not Applicable

BACKGROUND

The present invention relates to a film sealing and wrapping machinewith a rotary cut and seal jaw for wrapping a product with heat sealablematerial.

Prior art shrink wrap machines exist which are used to form a film bagaround a product in a high production environment. Extreme Packaging,Inc. located in Orange County, Calif. is a manufacturer of high qualityshrink wrap machines and has a philosophy of innovation and continuouslyimproving their machines to increase efficiency. Extreme Packaging, Inc.has been producing high quality shrink wrap machines for the past 10years.

The film sealing and wrapping machine discussed herein is an improvementof prior art shrink wrap machines.

BRIEF SUMMARY

The film sealing and wrapping machine discussed herein addresses thedeficiencies with respect to prior art shrink wrap machines.

A film sealing and wrapping machine generally forms a tube around aplurality of products. In a sealing and cutting section of the filmsealing and wrapping machine, cross seals and cuts are made betweenadjacent products to form individually film wrapped products. To improvethe through put of the film sealing and wrapping machine and provide fora stronger seal and tighter bag or film bag, the sealing and cuttingsection of the film sealing and wrapping machine discussed hereinincorporates one or more of the following aspects.

First, the sealing and cutting section has a rotary head with a slidingmechanism within rotary drums of the rotary head. The sliding mechanismprovides for smooth, non-jerky operation as the rotary drums traverse aseal bar and pressure pad along a circular path. The sliding mechanismis enclosed within a lubricated housing that requires less maintenanceand is quieter than geared mechanisms. The sliding mechanism hassubstantially less back lash compared to gearing systems. Since thesliding mechanism holds a tighter tolerance than gearing systems, thesliding mechanism encourages a more consistent positive pressure uponthe film which results in consistently stronger seals and positive bagcutoffs thereby producing fewer rejects and higher efficiencies.

Second, the rotational speed of the rotating drums are adjusted as afunction of product length and product height. The adjustments to thespeed of the rotary drums allow adjacent products to be placed closer toeach other and form smaller or tighter bags around each product therebyincreasing through put of the film sealing and wrapping machine and alsoproviding a tighter film bag.

Third, both the upper seal bar and the lower pressure pad may be springloaded such that as the seal bar and pressure pad contact each other,the point of contact between the seal bar and pressure pad traverses ina horizontal plane generally parallel to a path of travel of theproduct. As such, the film is not pushed, pulled or deformed due tovertical movement of the seal bar and pressure pad during the sealingand cutting process. Rather, the point of contact between the seal barand pressure pad is maintained parallel to the product's path of travelsuch that the seal bar and pressure pad forms a cross seal along thetube of film and cuts the tube of film without significantly disturbingthe film.

Fourth, the seal bar and pressure pad traverse a circular pathassociated with the rotation of the rotating drums. During the rotation,the seal bar and pressure pad has a horizontal component of movement(i.e., left to right and right to left). The sealing and cutting sectioncomprises a single belt that is guided by a series of pulleys upstreamand downstream of the seal bar and the pressure pad. The belt forms agap between which the seal bar and the pressure pad meet to performsealing and cutting steps. During rotation of the seal bar and pressurepad, the gap defined by the belt must track the horizontal location ofthe seal bar and the pressure pad. To this end, the gap is mechanicallylinked to the lower pressure pad through a control carriage.

Additionally, the seal bar and the pressure pad may both be heated suchas when sealing and wrapping cold products.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the various embodimentsdisclosed herein will be better understood with respect to the followingdescription and drawings, in which like numbers refer to like partsthroughout, and in which:

FIG. 1 is a perspective view of a film sealing and wrapping machine;

FIG. 2 is a cross sectional view of a sealing and cutting section of thefilm sealing and wrapping machine shown in FIG. 1;

FIG. 3 is an exploded view of a rotary drum of the sealing and cuttingsection shown in FIG. 1;

FIG. 4A is a cross sectional view of the rotary drum with a crank throwat a 6 o'clock position;

FIG. 4B is an illustration of the rotary drum shown in FIG. 4A with thecrank throw at a 9 o'clock position;

FIG. 4C illustrates the rotary drum shown in FIG. 4A with the crankthrow at a 12 o'clock position;

FIG. 4D illustrates the rotary drum of FIG. 4A with the crank throw at a3 o'clock position;

FIG. 5 is a cross sectional view of the sealing and cutting sectionshown in FIG. 1;

FIG. 6 illustrates upper and lower rotating drums as the seal bar andpressure pad are traversed; and

FIG. 7 is a perspective view of a control carriage.

DETAILED DESCRIPTION

Referring now to FIG. 1, a film sealing and wrapping machine 10 isshown. The film sealing and wrapping machine 10 may comprise a feed unit12, a wrapping section 14, a sealing and cutting section 16 and anoptional shrink tunnel 18. As product 20 is propelled into the wrappingsection 14, a film delivery system 22 supplies wrapping film 24 (seeFIG. 2) to the wrapping section 14. The wrapping film 24 forms a tubearound the plurality of products 20 being fed into the wrapping section14 by the feed unit 12. The sealing and cutting section 16, which isshown in FIGS. 1 and 2, supports the product 20 and the wrapping film 24(see FIG. 2). The product 20 traverses in a left to right direction(i.e., upstream to downstream direction) as shown by arrow 26 in FIG. 2.

The sealing and cutting section 16 comprises a rotary head assembly 28in which an upper seal bar 30 and a lower pressure pad 32 forms a crossseal on the tube of the wrapping film 24 and cuts the tube of wrappingfilm 24. When the film 24 on the front (i.e., downstream) side of theproduct 20 is sealed and cut and the film 24 on the rear (i.e.,upstream) side of the product 20 is sealed and cut, an individuallywrapped product 20 is provided downstream of the sealing and cuttingsection 16, as shown in FIG. 2.

The sealing and cutting section 16 incorporates one or more of fourunique aspects which will be discussed in detail below. First, therotary head assembly 28 has an internal sliding mechanism 34 (see FIG.3). The sliding mechanism 34 permits the upper seal bar 30 and the lowerpressure pad 32 to maintain its angular orientation (preferably,vertical) as upper and lower rotating drums 36, 38 (see FIG. 2) rotatein the direction shown by arrows 40, 42 (see FIG. 2). Additionally, thesliding mechanism 34 provides quiet operation of the sealing and cuttingsection 16. The upper and lower drums 36, 38 may be sealed and containlubricants such that lubrication and maintenance do not have to beperformed on a frequent basis. The sliding mechanism has substantiallyless back lash compared to gearing systems. Since the sliding mechanismholds a tighter tolerance than gearing systems, the sliding mechanismencourages a more consistent positive pressure upon the film whichresults in consistently stronger seals and positive bag cutoffs therebyproducing fewer rejects and higher efficiencies.

Second, the rotational speed of the upper and lower drums 36, 38 may becontinuously varied as a function of product height 44 (see FIG. 2),product length 46 (see FIG. 2) and angular position. By adjusting therotating speed of the upper and lower drums 36, 38, a wider range ofproducts may be wrapped by the film sealing and wrapping machine 10 anda tighter bag 52 (see FIG. 2) may be formed around the product 20. Also,a cleaner seal and cut is formed.

Third, the upper seal bar 30 and the lower pressure pad 32 are bothspring loaded. Beneficially, the spring forces of the upper seal bar 30and the lower pressure pad 32 may be adjusted such that the seal bar 30and pressure pad 32 may self align when in contact with each other suchthat the seal bar 30 and pressure pad 32 may apply even pressure on thefilm 24 and not distort the film 24.

Fourth, the sealing and cutting section 16 may comprise a single belt 48(see FIG. 2) that is wrapped around a plurality of pulleys 50 such thatthe belt 48 receives the product 20 and the tube of wrapping film 24upstream of the seal bar 30 and pressure pad 32 as well as receives theindividually wrapped product 20 in film bags 52 downstream of the sealbar 30 and pressure pad 32, as shown in FIG. 2. The belt 48 forms a gap54 (see FIG. 2) which is mechanically linked to a lateral position ofthe seal bar 30 and the pressure pad 32. As the upper and lower drums36, 38 rotate in the direction of arrows 40, 42, the lateral position ofthe seal bar 30 and pressure pad 32 reciprocates from a left to rightdirection and a right to left direction. The gap 54 mechanically tracksthe lateral position of the seal bar 30 and the pressure pad 32 througha control carriage mechanism.

As discussed above, one aspect of the sealing and cutting section 16 isthe internal sliding mechanism 34 which is shown in FIG. 3. The internalsliding mechanism 34 may comprise a slider 56 which slides in a lateraldirection along horizontal slide 58. The sliding mechanism 34 mayadditionally include a vertical slide 60 which slides in a verticaldirection with respect to the slider 56. A crank throw 62 may be mountedto the vertical slide 60 and may also be mounted to the seal bar 30 orthe pressure pad 32 as the situation dictates. As discussed above, theseal bar 30 and the pressure pad 32 maintain an angular orientation(preferably, vertical) as the upper and lower drums 36, 38 rotate. Theangular orientation is maintained because the horizontal slide 58 doesnot rotate but is fixed to a yoke 64 which is attached to a frame 66(see FIGS. 2 and 5) of the sealing and cutting section 16. Thehorizontal slide 58 remains stationary as the drums 36, 38 rotate. Theslider 56 slides horizontally along a path defined by the horizontalslide 58. The vertical slide 60 is traversed up and down along a groove68 of the slider 56. The yoke 64, horizontal slide 58, slider 56 and thevertical slide 60 do not rotate but longitudinally slide against eachother. This configuration allows the crank throw 62 to be located offcenter from a central rotating axis 140, 142 (see FIG. 6) of the drums36, 38 to permit circular motion of the seal bar 30 or the pressure pad32 and maintain angular orientation of the seal bar 30 and pressure pad32 throughout the entire rotation of the upper and lower drums 36, 38.

Referring now to FIG. 4A, one of the upper or lower drums 36, 38 isshown. The rotation of the drums 36, 38 may rotate in a clockwisedirection or a counterclockwise direction depending on whether the drumis the upper drum 36 or the lower drum 38. The upper and lower drums 36,38 rotate in reverse directions, as shown in FIG. 2. Accordingly, theconcepts discussed with respect to FIGS. 4A-4D may apply to the upperdrum 36 or the lower drum 38 but in an opposite manner. Beginning withFIG. 4A, the crank throw 62 is located at the 6 o'clock position. As thedrum 36, 38 rotates in a clockwise direction, the vertical slide 60 istraversed upward in the groove 68. Also, the slider 56 is traversed tothe left along the horizontal slide 58. Both sliding actions areaccomplished in a smooth and non-jerky fashion. Unlike gears with teeththat must have multiple teeth releasing and engaging throughout therotation, the sliding mechanism 34 does not have a gear with teeth.Rather, a smooth quiet sliding action is accomplished between lubricatedcomponents continuously in contact with each other. The slidingmechanism 34 is quieter than geared mechanisms and is not jerky becausethe sliding mechanism 34 does not engage and release multiple teeth atthe same time.

The crank throw 62 is now traversed from the 9 o'clock position shown inFIG. 4B to the 12 o'clock position shown in FIG. 4C. To this end, thecrank throw 62 is traversed upward as the vertical slide 60 continuesits upward traversal in groove 68. Also, the slider 56 traverses back tothe center. The crank throw 62 is traversed to the 3 o'clock position asshown in FIG. 4D then back to the 6 o'clock position as shown in FIG. 4Ato complete the cycle. As can be seen from the discussion above, theseal bar 30 and the pressure pad 32, which may be mounted to the crankthrow 62, maintains an angular orientation (preferably, verticalorientation) while also traversing along a circular path correspondingto a circular path 70 (shown in dash lines in FIGS. 4A-4D).

The upper and lower drums 36, 38 may additionally include a driventiming belt pulley 72 (see FIG. 3) which may be driven by belt 86 (seeFIG. 2). The belt 86 wraps around the upper drum 36 as well as the lowerdrum 38 so that the upper and lower drums 36, 38 rotate in reversedirections. The belt 86 may travel in a direction shown by arrow 88 (seeFIG. 2).

Referring back to FIG. 3, the upper and lower drums 36, 38 mayadditionally include a housing 90. The housing 90 may have a casing 92,a backing plate 94 and a cover plate 96. As discussed above, the yoke 64is fixedly attached to the frame 66 (see FIGS. 2 and 5) of the sealingand cutting section 16. However, it is also contemplated that the yoke64 may be attached to other stationary objects of the film sealing andwrapping machine 10. The yoke 64 may additionally have a post 98 uponwhich a bearing 100 is mounted. The backing plate 94 is initially pushedonto the yoke 64. To this end, the bearing 100 is disposed on the post98 as well as on an interior surface 102 of the backing plate 94. Thebacking plate 94 is also attached to the driven timing belt pulley 72 bybolts 104. As the belt 86 (see FIG. 2) drives the driven timing beltpulley 72, the backing plate 94 rotates the cover plate 96 but the yoke64 does not rotate. The bearing 100 is retained on the post 98 byretaining ring 106 which fits within retaining ring groove 108. Thehorizontal slide 58 is mounted to the post 98 with bolts 110. The casing92 is attached to the backing plate 94 with bolts 112.

The slider 56 may have a groove 114. The horizontal slide 58 is receivedwithin the groove 114. The engagement of the horizontal slide 58 and thehorizontal groove 114 of the slider 56 limits movement of the slider 56to horizontal left and right movements. The vertical slide 60 and thecrank throw 62 may be fixedly attached to each other by bolt 118. Thecrank throw 62 may have a post 120 upon which a bearing 122 is mounted.The bearing 122 is retained on the post 120 by retaining ring 124 fittedwithin a groove of the post 120. The crank throw 62 is mounted to thecover plate 96 by mounting bearing 122 in an aperture 126 of the coverplate 96. The cover plate 96 is mounted to the casing 92 via bolts 128.When mounted, the vertical slide 60 is disposed within groove 68 of theslider 56.

The belt 86 drives the driven timing belt pulley 72 in either aclockwise or counterclockwise direction depending on whether the belt 86is driving the upper or lower drum 36, 38. Rotational motion is impartedto the bearing 122 and the crank throw 62 by the cover plate 96. Theangular orientation of the corresponding seal bar 30 or pressure pad 32remains constant throughout the entire travel of the corresponding sealbar 30 or pressure pad 32 along a circular path corresponding to thecircular path 70. To this end, the vertical slide 60 slides withingroove 68 of the slider 56 and the slider 56 slides along the horizontalslide 58 as discussed above in relation to FIGS. 4A-4D.

Although the sliding mechanism 34 discussed above shows the horizontalslide 58 in a generally horizontal orientation and the vertical slide 60traversing along a generally vertical path, the slide 58 may bepositioned at any angle (i.e., 360 degrees). Nonetheless, the groove 68of the slider 56 and the groove 114 of the slider 56 are generallyperpendicular to each other. Accordingly, the slider 56 and the slide 60traverse along paths that are perpendicular to each other.

Referring now to FIG. 5, two rotating upper drums 36 confer rotation onthe upper seal bar 30 along its circular path during rotation of theupper drums 36. The upper drums 36 are connected to the seal bar 30 inthe following manner. The post 120 of the crank throw 62 (see FIGS. 3and 5) for each upper drum 36 is attached to opposed distal end portionsof a main upper cross bar 130. The seal bar 30 is attached in a springloaded manner to the main upper cross bar 130. The lower pressure pad 32may also be attached to the lower rotating drums 38 in a similarfashion. In particular, the post 120 (see FIGS. 3 and 5) of each lowerrotating drum 38 may be attached to a lower main cross bar 132 which issubsequently attached to the lower pressure pad 32 in a spring loadedmanner. Note that the yokes 64 of the upper and lower drums 36, 38 areattached to the frame 66 of the sealing and cutting section 16, asdiscussed above.

As discussed above, the spring loaded aspect of the seal bar 30 and thepressure pad 32 provides certain benefits as discussed herein. By way ofexample and not limitation, the spring loaded upper seal bar 30 and thespring loaded lower pressure pad 32 are self-aligning. For example, ifthe left side of the upper seal bar 30 and the lower pressure pad 32contacts before the right side thereof 30, 32, or vice versa, thesprings level the upper seal bar 30 and the lower pressure pad 32 toeach other. It is also contemplated that the stroke of the spring may beadjustably increased or decreased with an adjustment nut or screw torespectively increase or decrease the dwell time (i.e., contact time) ofthe upper seal bar 30 and the lower pressure pad 32. The strokeadjustment encourages improved sealing and cutting of a greater range offilm gauges and formulations (i.e., types).

Referring now to FIG. 6, before the seal bar 30 and the pressure pad 32contact each other, the springs 134 a-f (see FIGS. 5 and 6) of the sealbar 30 are preloaded. Springs 134 a-f are shown as one spring forclarity in FIG. 6. Likewise, the springs 136 a-c (see FIGS. 5 and 6) ofthe lower pressure pad 32 are preloaded. Springs 136 a-c are shown asone spring for clarity in FIG. 6. The springs 134 a-f are preloaded tohave a cumulative spring force about equal to the cumulative springforce of the springs 136 a-c. It is contemplated that the preload on thesprings 134 a-f and/or springs 136 a-c may be adjusted via a nut. Also,it is contemplated that the spring force of the springs 134 a-f and/orsprings 136 a-c may be adjusted via a nut or by replacing the springswith stronger or weaker springs. Also, the spring constant of thesprings 134 a-f as a whole is about equal to the spring constant of thesprings 136 a-c as a whole.

As the upper and lower drums 36, 38 rotate, the seal bar 30 and thepressure pad 32 make contact (see pt. B in FIG. 6) with each other andthe film 24 (film not shown in FIG. 6 for clarity). As the upper andlower drums 36, 38 continue to rotate, the seal bar 30 maintains contactwith the pressure pad 32. Moreover, the point of contact between theseal bar 30 and the pressure pad 32 is generally maintained within aplane defined by the path of travel 138 of the product 20. Preferably,the point of contact between the seal bar 30 and the pressure pad 32 islocated at a midpoint between a rotating axis 140 of the upper rotatingdrum 36 and a rotating axis 142 of the lower rotating drum 38. The pointof contact is also preferably aligned to about a vertical midpoint 144of the product 20. Since the contact point between the seal bar 30 andthe pressure pad 32 is maintained at generally the midpoint 144 of theproduct 20 or at a constant point as the film 24 is being sealed and cutby the sealing and cutting section 16, the seal bar 30 and the pressurepad 32 do not deform the film 24 during the sealing and cutting process.The seal bar 30 and the pressure pad 32 maintain contact for a definedangle of rotation 146 as well as a defined linear length 148corresponding to the angle of rotation 146. After the upper and lowerrotating drums 36, 38 have proceeded through the angle of rotation 146,the seal bar 30 disengages the pressure pad 32 after point C shown inFIG. 6.

Referring now to FIG. 5, springs 136 a-c are disposed between the lowerpressure pad 32 and the lower main cross bar 132. Guide rods 156 a, bare disposed within sleeves 158 a, b and attached to the pressure pad32. In relation to the seal bar 30, the same is attached to the mainupper cross bar 130 with guide rods 156 c, d. The guide rods 156 c, dare spring loaded with the springs 134 a, f. Springs 134 b-e alsoprovide a downward spring force to the seal bar 30. If the seal bar 30is spring loaded and the pressure pad 32 is not spring loaded, then thesprings 134 a-f must deflect the entire amount to ensure proper sealingand cutting of the film 24. Fortunately, in the film sealing andwrapping machine 10 discussed herein, the upper seal bar 30 and thepressure pad 32 may both be spring loaded. The springs 136 a-c and thesprings 134 a-f each deflect a smaller amount compared to the situationwhere only the upper seal bar 30 is spring loaded or only the lowerpressure pad 32 is spring loaded. This allows a higher throughputthrough the rotary head assembly 28.

The film sealing and wrapping machine 10 is capable of forming film bags52 (see FIG. 2) around products 20 of various lengths 46 (see FIGS. 2and 6) and heights 44 (see FIGS. 2 and 6). The products 20 flow throughthe machine 10 along the path of travel 138 (see FIG. 6) in a sequentialmanner one after the other. The sealing and cutting section 16 seals thetube of film 24 and cuts the same between adjacent products 20. In thismanner, the product 20 is enclosed within the bag 52 of film. The speedof rotation of the upper and lower drums 36, 38 is adjusted to theproduct length 46 and the product height 44 to prevent the seal bar 30and the pressure pad 32 from hitting adjacent products 20 as the sealbar 30 and pressure pad 32 enter a gap 55 (see FIGS. 2 and 6). Also, thespeed of rotation of the upper and lower drums 36, 38 is adjusted to theproduct length 46 and the product height 44 to prevent the seal bar 30and the pressure pad 32 from hitting adjacent products 20 as the sealbar 30 and pressure pad 32 leave the gap 55.

The seal bar 30 and the pressure pad 32 must make one revolution fromone gap 55 defined by adjacent products 20 to the next gap 55 defined bysubsequent adjacent products. The time it takes the seal bar 30 and thepressure pad 32 to make one revolution must generally equal the time ittakes two gaps 55 to pass the same point in the sealing and cuttingsection 16. The sealing and cutting section 16 seals the film 24 at thefrontal (i.e., downstream) end of the product 20. When the seal bar 30and the pressure pad 32 are in contact with each other (i.e., during theangle of rotation) the horizontal speed 150, 152 of the seal bar 30 andthe pressure pad 32 is generally equal to the speed of the product 20 orbelt 48. This prevents the seal bar 30 and the pressure pad 32 frompushing or pulling the film 24 thereby preventing deformation of thefilm 24.

After the seal bar 30 and the pressure pad 32 rotate through the angleof rotation 146, the speed of the rotating drums 36, 38 may be changed(e.g., accelerated) such that the seal bar 30 and the pressure pad 32moves out of the way of the upstream product 20 and does not hit theback end of the adjacent downstream product 20. For example, after theseal bar 30 and pressure pad 32 has cleared adjacent products 20, theseal bar 30 and the pressure pad 32 may be accelerated to its outer mostposition. For the seal bar 30, this is the 12 o'clock position. For thepressure pad 32, this is the 6 o'clock position. For long products, theproduct 20 passes between the seal bar 30 and the pressure pad 32 whilethe seal bar 30 and the pressure pad 32 wait (i.e., stop) at this outermost position. As the back end of the product 20 approaches the seal bar30 and pressure pad 32, the upper and lower rotating drums 36, 38 rotateand accelerate the upper seal bar 30 and the pressure pad 32 between theupcoming gap 55. The rotational cycle of the drums 36, 38 is thencompleted. In this manner, the rotating drums 36, 38 rotate onerevolution for each product or bag length.

For long products (i.e., products that require a bag length greater thana circumference of the circular path 70), the horizontal travel speed ofthe seal bar 30 and pressure pad 32 during contact is equal to thehorizontal speed of the product 20 but at some point after the angle ofrotation 146, the rotational speed of the upper and lower drums 36, 38slows down or stops such that the time for one revolution of the upperand lower drums 36, 38 is equal to the time required for one bag lengthto pass through the sealing and cutting section 16. Conversely, forproducts that require a short bag length (i.e., a bag length which isless than a circumference of the circular path 70), the rotational speedof the upper and lower drums 36, 38 is at some point accelerated afterthe angle of rotation 146 such that the time for one revolution of theupper and lower drums 36, 38 is equal to the time for one bag length totraverse through the sealing and cutting section 16.

For thin products, there is little or no risk that the seal bar 30 andthe pressure pad 32 will hit the front end of the incoming product 20 orhit the back end of the outgoing product 20. As such, the rotationalspeed of the upper and lower drums 36, 38 may be adjusted (e.g.,accelerated) immediately before and after the angle of rotation 146.However, for thicker products, the seal bar 30 and pressure pad 32 mayhit the front end of the incoming product 20 as the seal bar 30 andpressure pad 32 approach each other to begin the sealing and cuttingprocess. Also, the seal bar 30 and pressure pad 32 may hit the back endof the outgoing product 20 after completion of the sealing and cuttingprocess. To mitigate this risk, the horizontal speed 150, 152 (see FIG.6) of the seal bar 30 and the pressure pad 32 may equal the speed ofproduct 20 or belt 48 traveling through the sealing and cutting section16 for a greater angle than the angle of rotation 146. When thehorizontal speed of the seal bar 30 and the pressure pad 32 is equal tothe belt speed of the sealing and cutting section 16 or product 20, theseal bar 30 and the pressure pad 32 is said to have a position lock onthe products 20 or belt 48. The amount of position lock varies as afunction of product height 44. For thin products, the amount of positionlock equals the angle of rotation 146. For thicker products, the amountof position lock can theoretically occur at the 9 o'clock position tothe 3 o'clock position for the upper drum 36. By way of example and notlimitation, the amount of position lock is approximately 30 degrees oneither side when the seal bar 30 is at the 6 o'clock position andpressure pad 32 is at the 12 o'clock position (see FIG. 6).

For most lengths and thicknesses of products, the horizontal speed ofthe seal bar 30 and the pressure pad 32 during the angle of rotation 146is equal to the linear speed of the belt 48. For products 20 thatrequire a bag length shorter than the circumference of the circular path70 (see FIG. 4A) of the drum 36, 38, the rotational speed of the drums36, 38 must be accelerated at some point after the angle of rotation 146such that the time for one revolution of the drums 36, 38 is equal tothe time for one bag length to traverse through the sealing and cuttingsection 16. For short and thin products, the speed of the drums 36, 38may be accelerated immediately after the angle of rotation 146. However,for short but thicker products, the amount of position lock increases toan amount greater than the angle of rotation 146 to an extent that theseal bar 30 and pressure pad 32 may be accelerated out of the gap 55 orinto the gap 55 without hitting adjacent products 20.

For long but thin products, during the angle of rotation 146, thehorizontal speed 150, 152 of the seal bar 30 and the pressure pad 32 isequal to the linear speed of the belt 48. Long products require a baglength greater than the circumference of the circular path 70 of thedrum 36, 38. After the angle of rotation 146, the seal bar 30 and thepressure pad 32 has additional time to make one revolution since the baglength is greater than a circumference of the circular path of travel70. As such, the seal bar 30 and the pressure pad 32 may be accelerated,decelerated, or a combination thereof to the outermost position andstopped to wait for the subsequent gap 55 between adjacent products 20.Alternatively, the seal bar 30 and the pressure pad 32 may be sloweddown or decelerated to synchronize the seal bar 30 and the pressure pad32 to meet up with the subsequent gap 55. As the thickness of the longproduct 20 increases, the amount of position lock increases to an amountgreater than the angle of rotation 146 to an extent that the seal bar 30and pressure pad 32 may be accelerated out of the gap 55 or into the gap55 without hitting adjacent products 20. The seal bar 30 and thepressure pad 32 may be accelerated to its outermost position and stoppedto wait for the subsequent gap 55 between adjacent products 20 or theseal bar 30 and the pressure pad 32 may be decelerated to time the sealbar 30 and the pressure pad 32 to meet up with the subsequent gap 55.Alternatively, it is contemplated that after the angle of rotation 146,the seal bar 30 and the pressure pad 32 may be accelerated out of thegap 55 to clear the product 20 then decelerated or stopped at itsoutermost position. As the upcoming gap 55 approaches, the seal bar 30and the pressure pad 32 may be accelerated into the upcoming gap 55. Atsome point, the horizontal speed 150, 152 of the seal bar 30 andpressure pad 32 may be adjusted to establish position lock.

Referring now to FIG. 7, a perspective view of a lower rotating drum 38is shown. The lower rotating drum 38 is driven by belt 86 travelling inthe direction 88. As shown in FIG. 2, the belt 48 upon which the product20 rests upon is a single belt that loops through pulleys 50. The singlebelt 48 is located downstream and upstream of the seal bar 30 and thepressure pad 32 to form the gap 54 which tracks the horizontal positionof the seal bar 30 and the pressure pad 32. In order for the gap 54 totrack the position of the seal bar 30 and pressure pad 32, the lowermain cross bar 132 (see FIG. 7) may be mechanically connected to anelongate bar 160. The elongate bar 160 may extend downwardly. Theelongate bar 150 may be engaged through a linear bearing box 162 withinwhich there is a linear bearing that allows the bar 160 to slidevertically up and down as the lower main cross bar 132 follows thecircular path 70 and as the lower drum 38 rotates. The elongate bar 160also imposes horizontal forces to push a carriage 164 left and right.The rollers 50 a, b which define the gap 54 may be mounted to thecarriage 164. In this manner, the gap 54 tracks the horizontal positionof the seal bar 30 and the pressure pad 32.

In a further aspect of the sealing and cutting section 16, the upperseal bar 30 and the lower pressure pad 32 may both be heated. This isespecially useful for running cold or frozen products which removeresidual heat from the seal pad during the sealing and cutting process.The additional heat from the pressure pad 32 provides for a strongerseal at higher speeds or through put.

In an aspect of the film sealing and wrapping machine, the film may be ashrink wrap film, polyolefin, polyethylene, PVC, etc.

The above description is given by way of example, and not limitation.Given the above disclosure, one skilled in the art could devisevariations that are within the scope and spirit of the inventiondisclosed herein, including various ways of spring loading the seal bar30 and the pressure pad 32. Further, the various features of theembodiments disclosed herein can be used alone, or in varyingcombinations with each other and are not intended to be limited to thespecific combination described herein. Thus, the scope of the claims isnot to be limited by the illustrated embodiments.

What is claimed is:
 1. A rotary sealing and cutting jaw for a filmsealing and wrapping machine, the rotary sealing and cutting jawcomprising: a first cross member traveling along a first circular pathwhich is equidistant from a first central rotating axis and maintainingan angular orientation of the first cross member during the entire firstcircular path; a first rotary member attached to the first cross memberwherein the first rotary member rotates about the first central rotatingaxis, a first caming mechanism incorporated into the first rotarymember, the first caming mechanism allowing the first cross member totravel along the first circular path and to maintain the angularorientation of the first cross member during the entire first circularpath; a second cross member traveling along a second circular path whichis equidistant from a second central rotating axis and maintaining anangular orientation of the second cross member during the entire secondcircular path; a second rotary member attached to the second crossmember wherein the second rotary member rotates about the second centralrotating axis, a second caming mechanism incorporated into the secondrotary member, the second caming mechanism allowing the second crossmember to travel along the second circular path and to maintain theangular orientation of the second cross member during the entire secondcircular path; wherein the second rotary member and the second crossmember are disposed opposite from the first rotary member and the firstcross member; wherein the first caming mechanism has first and secondstraight surfaces which are perpendicular to each other and the secondstraight cam surface is a groove formed in the slider.
 2. The jaw ofclaim 1 wherein the first straight surface is a groove formed in aslider.
 3. The jaw of claim 1 wherein the first rotary member is a firstrotary drum with the first caming mechanism disposed within the firstrotary drum and second rotary member is a second rotary drum with thesecond caming mechanism disposed within the second rotary drum.
 4. Thejaw of claim 3 wherein the first rotary drum has a cylindrical shellconfiguration with the first caming mechanism disposed therewithin, andthe second rotary drum is a cylindrical shell configuration with thesecond caming mechanism disposed therewithin.
 5. A method of operating arotary sealing and cutting jaw, the method comprising the steps of:rotating a first rotary drum attached to a first cross member so thatthe first cross member travels along a complete first circular path,wherein the first rotary drum includes a caming mechanism disposedwithin the first rotary drum to maintain a constant angular position ofthe first cross member along the complete first circular path; rotatinga second rotary drum attached to a second cross member so that thesecond cross member travels along a complete second circular path,wherein the second rotary drum includes as caming mechanism disposedwithin the second rotary drum to maintain a constant angular position ofthe second cross member along the complete second circular path;synchronizing rotation of the first and second cross members so that thecross members approach and move apart from each other for eachrotational cycle of the first and second rotary mechanisms; maintainingan angular orientation of the first and second cross members throughoutthe complete first and second circular paths; sliding a first drivenmember disposed within the first rotary drum and attached to the firstcross member against a first straight cam surface of a first sliderdisposed within the first rotary drum; sliding a second driven memberdisposed within the second rotary drum and attached to the second crossmember against a second straight cam surface of a second slider disposedwithin the second rotary drum; and traversing the first and secondsliders in a first direction and the first and second driven members ina second direction perpendicular to the first direction against thefirst and second straight cam surfaces.
 6. The method of claim 5 furthercomprising the step of continuously lubricating the first and second camactuated rotary drums during operation of the jaw.
 7. The method ofclaim 5 wherein the first direction is horizontal and the seconddirection is vertical.